The Program Project seeks to enhance the ability of ultrasonic imaging to detect and characterize tumors. This area was chosen because of the widespread use of ultrasonic imaging in practically all medical specialists. The improvements that we seek, selected to make ultrasonic imaging even more useful, would thus have a large impact upon medical practice. They would contribute to oncology through improved detection, diagnosis and treatment monitoring. The program consists primarily of projects that take different approaches to the problem of processing the original echo data to form images. These projects are based on new approaches as well as on adaptations of approaches that have been successful in industrial non-destructive testing and in optics. Our program provides laboratory and clinical cores for joint data collection, and assuring interaction and coordination between the projects and between imaging modalities (US, CT and MRI) and pathology. This structure should remove many of the problems that have been encountered when attempting to improve ultrasonic tissue characterization through individual research projects. Also, the clinical collaborators will benefit from having available a variety of image formation methods to evaluate for different purposes. The inter- comparison with other modalities can thus be efficiently handled. One project will integrate doppler flow data from small vessels into the data set. To assure that this program remains current as ultrasonic methodology advances during the term of the grant we have included work in related areas. Some type of contrast agent will most likely be widely used in the near future. Therefore, we have included a project that is developing two promising new contrast agents. This project also will allow us to gain experience with characterizing these materials and offer guidance on the use of contrast in enhancing image features associated with tumors. A transducer and measurement system project has been completed so that we are able to perform ultrasonic dosimetry. This project will now develop transducers for wideband data collection that is needed for the projects that are developing new methods, and will be convenient for clinical use. A major effort is planned in assessing the improvements in imaging by direct comparison to existing images. These include feature extraction methods to evaluate the existing data, and a new effort in Receive Operating Characteristic (ROC) analysis for additional testing using new data sets.